Gnarwails are neutral toward players. They regularly chase other Ocean Fishes and eat their meat.
When attacked, they will drill Boats with their Horn, damaging them and creating a leak. When drilling, the Horn can be attacked and destroyed without killing the Gnarwail, dropping one Gnarwail Horn. If a Gnarwail doesn't have a horn, it will attack by creating Waves in the ocean.
Gnarwails can be befriended by giving them Meats. They follow for 25 per day for up to 2.5 days. Follower Gnarwails will regularly toss Items floating in the Ocean towards the player.